Gauge restraint measurement system

ABSTRACT

A direct measuring loaded gage axle assembly that measures track strength by directly measuring constant load on split axles as vertical loads are imposed by a hydraulic ram, and horizontal loads being supplied by horizontal rams through split axles and steel wheels to the railroad tracks enabling improved calibration to measure changes in track gauge indicating track strength condition and further including electronic data recording and comparison.

This application claims priority from U.S. Provisional Application Ser.No. 60/437,467 filed Dec. 31, 2002.

BACKGROUND

This disclosure relates to improvements in measurement and calibrationof apparatus used for testing the track strength of railroad track, tieand fastener conditions using a loaded gauge axle assembly which impartsa calibrated downward force and a calibrated outward force on the rails,and measures the load applied to the rails to determine the strength ofthe rails, ties and fasteners.

By way of background but not limitation, various types of measurementand calibration devices are utilized by the industry for testingstrength of railroad tracks, ties and fasteners including a “GaugeRestraint Measurement System (GRMS)” from the U.S. Department ofTransportation also described in an article entitled “AAR's TrackLoading Vehicle” and U.S. Pat. No. 5,756,903 issued May 26, 1998. Theteachings of said U.S. Pat. No. 5,756,903 are incorporated by referenceas if fully set forth herein.

The track strength testing vehicle of U.S. Pat. No. 5,756,903 measureschanges in hydraulic fluid pressure to determine both changes in loaddue to track strength changes and to control the load applied.

This system introduces potential error in the measurements because offactors such as time lag between changes at the wheel and measurement ofpressure, errors introduced by pressure changes made to preserve load atthe wheel, and the number of components, instruments and calculationsinvolved. This system does not account for frictional forces within thesplit-axle assembly and cannot be used as a true rail/wheel forcethrough direct transducer measurement.

While the track strength testing taught in U.S. Pat. No. 5,756,903 isbelieved to be reliable and cost effective, its measurement system isbelieved to be somewhat over-inclusive, in that the statisticalvariations result in indications of track failure, when in fact thetrack is within specifications. Improved accuracy, therefore, can beexpected to have economic and time saving benefits in minimizingunnecessary repairs, and operational benefits in the ability to reliablyand rapidly locate those areas in need of repair.

The testing apparatus of U.S. Pat. No. 5,756,903 is a significantimprovement over the very large sized competitive track testing machinesin that the load gauge axle assembly can be comparatively easily removedand replaced, both for maintenance, and also for calibration. Under thearrangement of U.S. Pat. No. 5,756,903 complete calibration isaccomplished by removal of the axle assembly and testing in a laboratoryor shop. Field calibration can only be accomplished on certaincomponents and systems. Rail car mounted testing apparatus, or trackmaintenance apparatus the size and mass of rail cars are even moredifficult to calibrate, as the size of the vehicle and its componentsessentially requires removal from service and return to a shop.

In view of the above, it should be appreciated that there is a need fora device that accurately measures track strength and permits expedientcalibration of the measurement device. The present disclosure satisfiesthese and other needs and provides further related advantages.

SUMMARY

The disclosure comprises a direct measuring loaded gauge axle assemblythat measures track strength by directly measuring loads on split axlesas vertical loads are imposed by hydraulic rams. Horizontal loads aresupplied by a horizontal ram through split axles and flanged steelwheels to the rail head of the railroad tracks, enabling improvedcalibration to measure track strength and electronic data recording andcomparison.

Other features and advantages of the disclosure will be set forth inpart in the description which follows and the accompanying drawings,wherein the embodiments of the disclosure are described and shown, andin part will become apparent upon examination of the following detaileddescription taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The above mentioned and other features of this disclosure and the mannerof obtaining them will become more apparent and the disclosure will bebest understood by reference to the following description of embodimentsof the disclosure taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a side elevational view of the motor vehicle and loaded gaugeaxle track strength apparatus on a railroad track;

FIG. 2 is a top plan view of the motor vehicle body and loaded gaugeaxle track strength apparatus with the body portion in section to showthe arrangements;

FIG. 3 is a front elevational view of the loaded gauge axle trackstrength apparatus with the calibration assembly with the calibrationsubsystem;

FIG. 4 is a left side elevational view of the loaded gauge axle trackstrength apparatus with the calibration subsystem;

FIG. 5 is a top plan view of a first side of the prior art loaded gaugeaxle track strength with the load cell sensor embodiment;

FIG. 6 is a front sectional view of a first side of the prior art loadedgauge axle track strength apparatus with the load cell sensorembodiment;

FIG. 7 is a top plan view of a second side of the loaded gauge axletrack strength apparatus;

FIG. 8 is a front sectional view of a second side of the loaded gaugeaxle track strength apparatus;

FIG. 9 is a display of the data collected by the loaded gauge axle trackstrength apparatus;

FIG. 10 is a plot of results from the prior art load loaded gauge axletrack strength apparatus;

FIG. 11 is a plot of results from the improved loaded gauge axle trackstrength apparatus;

FIG. 12 is a flow chart of the load axle calibration subsystem; and

FIG. 13 is an exploded view of the loaded gauge axle track strengthapparatus.

DETAILED DESCRIPTION

While the present disclosure will be described fully hereinafter withreference to the accompanying drawings, in which a particular embodimentis shown, it is to be understood at the outset that persons skilled inthe art may modify the disclosure herein described while still achievingthe desired result. Accordingly, the description that follows is to beunderstood as a broad informative disclosure directed to persons skilledin the appropriate art and not as limitations on the present disclosure.

As illustrated in the drawings, the truck vehicle 10 has road wheels 12and high rail wheels 14. This arrangement enables operation of thevehicle on ordinary roads, driving to railroad tracks 16 and straddlingthem, then actuating the retractable high rail wheels 14 to partiallylift the truck off the rails 17. Motive drive is nevertheless stillprovided with the road wheels through the rubber tires 18. Gauge axleassembly 20 is located between the truck wheels 12.

The high rail units 14 are preferably forward of the front end 22 andrearward of the rear end 24 of the vehicle, forward of the front end 22on a front frame extension 26 and rearward of the rear end 24 on a frameextension 28, as shown in FIG. 1.

The gauge axle assembly 20 is used to apply a calibrated side load onthe tracks 16. Variation in track side load is measured by the gaugeaxle assembly 20 and the measurements taken are analyzed to determinethe strength of the track 16 by measuring variations in hydraulicpressure as load is also placed on the gauge axle. Split axle assembly30 made up left and right generally square sectioned shafts 32, 34 eachhaving a spindle 36, 38 on its outboard end 40, 42, as generallydiscussed in U.S. Pat. No. 5,756,903 and as shown in FIGS. 6 and 8.

Spindles 36, 38 and bearings 44 have wheels 46. Wheels 46 have surfaces48 that diverge toward flange 50. Bearing races 49 and 51 in the wheel46 and on the spindles 36, 38 have thrust and support surfaces.

At the inboard ends 52, 54 a hydraulic ram 56 is attached to clevis andpin fittings 58, 60. Ram 56 provides the outward force necessary for theflange 50 of the wheel 46 to maintain contact with the head 19 of thetracks 16. Shafts 32, 34 are carried on ultra high molecular weight(UHMW) plastic slides 62, 64 in housing 66.

An improvement in this application, compared to U.S. Pat. No. 5,756,903is in major measurement improvements enabled by new split axle shafts232, 234, or 332, 334 that incorporate force sensors positioned on theshafts.

As described in the aforementioned patent, distortion or variation inhydraulic pressure is directly measured by a linear transducer on thehydraulic line pressurizing ram 56. Track strength is then calculated bycomparing the measured pressure under a constant lateral load to anunloaded gauge measurement and a delta gauge or a rail movement iscomputed. Because this system measures fluid pressure, there is a slighttime lag in obtaining reading, rendering it difficult to accurate logmeasurements. Certain inaccuracies in the system occur due to physicalproperties of hydraulic fluid and friction in the hydraulic system,which results in a greater deviation in the numbers calculated thandesired.

In order to have a substantially constant load applied to the wheels 46in the prior art systems, hydraulic pressure in the hydraulic ram 56needs to be constantly adjusted. When a track weakness, caused by rail,tie or fastener failure, permits the wheels 46 to move, movement of thehydraulic piston in the hydraulic ram 56 causes the volume in thehydraulic system to increase, decreasing fluid pressure in the system.To compensate for movement of the piston of the hydraulic ram 56, systemhydraulic pressure is increased by the controls.

When the track returns to a gauge closer to the desired mean gauge inthe specification, there is a consequent decrease in volume in thecylinder of the hydraulic ram 56, increasing fluid pressure in thesystem. To compensate for movement of the piston of the hydraulic ram56, system pressure is reduced by the controls. Compensation in thesystem for fluxation in pressure creates a large disparity in theresultant measurements.

Because of the great deviation, caused by the fluxation in cylindervolume, railroads unnecessarily stop and physically inspect track thatin fact is within specification, which reduces the efficiency ofmaintenance operations and increases maintenance costs. These plots ofthe open loop hydraulic system utilizing force measurements taken off ofthe hydraulic system are shown in FIG. 10. The more accurate results ofthe improvement, described below, are shown in FIG. 11.

The present disclosure addresses these undesirable traits by usingdirect mechanical measurement of changes in load or strain in split axleshafts 232, 332 as shown in FIGS. 5–8. The axle assembly measureschanges in load or strain in each of the split axle shafts 232, 332. Theaxle assembly 20 applies a lateral load by use of hydraulic ram 56 andapplies a vertical load with use of hydraulic cylinders 82. The axleassembly 20 will be described regarding one side of the loaded gaugeaxle assembly 20, it being understood the other side is a mirror image.Shaft 232, of the first embodiment of the present disclosure, uses loadcells 256, 258 while shaft 332, of the second embodiment of the presentdisclosure, uses strain sensors 356, 358. Either the strain sensors 356,358 or the load cells 256, 258 provide essentially instantaneousmeasurement of changes in load on the split axle shafts 232, 332. Theinstallation of force transducers, such as the load cells 256, 258 inthe cantilevered section of the split axle shafts 232 or 332 outside ofthe frictional elements of the axle assembly 20 subjects the load cells256, 258 to rail/wheel forces and not frictional forces created by thehydraulic ram 56. The avoidance of frictional forces at the measurementpoint permits a more accurate detection of lateral weakness in theanalyzed track.

Vertical and lateral forces placed upon the track are separately andindependently, measured by the load cells 256, 258. The direct forcevertical and lateral measurement in the non-rotating split axle shafts232 is continuous along the running track. The orientation of the loadcells 256, 258 within each of the split axle shafts 232 determineswhether the analog output load cells 256 will be lateral load output orvertical load output. The load cells 256, 258 are designed so that theorientation of the load cell within an opening determines whether theforces measured are lateral or vertical. The load cells includealignment markings wherein the orientation of the markings dictates thetype of force measured. Positioning the alignment markings in a verticalorientation allows the load cells to measure lateral force andpositioning the alignment markings of the load cells forty five degreesfrom vertical permits the load cells to measure vertical force. Whileorienting load cells within the split axle shafts 232 in the describedconfiguration is the preferred method of measuring forces in the splitaxle shafts 232, other configurations of the load cells for measuringlateral and vertical forces may also be used to achieve the same result.Further, other possible force measuring devices that may be used tomeasure vertical and lateral forces within the split axle shafts 232.

Split axle shaft 232 includes a spindle 36 at the outboard end 240 asshown in FIG. 8. The spindle is adapted to accept bearings 44 and wheel46. Wheel 46 includes surfaces 37 that diverge toward a flange 50. Thewheel 46 and flange 50 are positioned on the head 19 of the rail 16.Bearing races 49 and 51 in the wheel 46 and on the spindles 36, 38 havethrust and support surfaces to prevent lateral and vertical play betweenthe wheel 46 and the split axle shaft 232. The use of bearings 44permits the wheel 46 to rotate along the track while the split axleshaft 232 remains stationary. This is necessary so that the orientationof the load cells 256, 258 remain constant.

At the inboard end 252 of each of the split axle shafts 232 thehydraulic ram 56 is attached by clevis and pin fittings 58, 60. Thehydraulic ram 56 is expanded and contracted by varying pressure on bothends of the cylinder within the hydraulic ram 56 in response to signalsfrom the load cells 256, 258. The hydraulic ram 56 is designed to pulland push the split axle shafts 232 so that a constant force is appliedto the tracks. Using a closed loop system, as described below, asubstantially constant lateral force and a substantially constantvertical force in an allowable range set by the FRA for GRMS measurementis applied to the tested track.

The split axle shafts 232 are located at opposite ends of the hydraulicram 56 and are slidably disposed within a housing 66, as shown in FIG.13. One skilled in the art will recognize that FIG. 13 is merely aclarification of the axle assembly 20 of FIGS. 3–8. The housing 66includes inner support channels 67, wherein the inner support channels67 slide with respect to the housing 66. The inner support channels 67are secured to the split axle shafts 232. To permit movement of theinner support channels 67 with respect to the housing, ultra highmolecular weight (UHMW) plastic slides 62, 64 are used.

Spaced in from end 240 of the split axle shaft 232 is a load sensingregion 242, as shown in FIGS. 7 and 8. In the first embodiment,utilizing load cells 256, 258, load sensing region 242 is machined orformed to define two opposed recesses 244, 246 in side surfaces 247 ofthe split axle shafts 232. The recesses 244, 246 are vertically formed,so that the full height of split axle shaft 232 is intact, but the widthis reduced by about sixty percent, each recess having a depth of about30 percent, with the remaining solid portion forming a web 250comprising about 40 percent of the width of split axle shaft 232.

The web 250, positioned between the recesses 244, 246, is itself boredto provide two apertures 252, 254 to receive load cells 256, 258, forwhich the leads 260 are lead away from the apertures in groove 262 toprotect the wiring for the load cells 256, 258 as shown in FIG. 7.During the application of lateral and vertical forces by hydraulic ram56 and cylinders 82, the apertures 252, 254 slightly deform, exertingpressure on the load cells 256, 258. The force exerted on the load cells256, 258 is translated into analog signals that are transmitted to asignal conditioning amplifier.

The load cells 256, 258 are tubular members that are adapted to measureforce applied to their structure. The load cells 256, 258 are designedso that their orientation within the apertures 252, 254 determinewhether the output for a given cell relates to vertical or lateral load.To measure lateral force on the split axle shaft 232, the alignmentmarkings of the load cell 256 are positioned in a vertical orientationwithin the aperture 252. To measure vertical force on the split axleshaft 232, the alignment markings of the load cell 258 are positionedforty five degrees from vertical. The load cells 256, 258 continuouslymeasure lateral and vertical force applied to the rails, the values ofwhich are recorded. While orienting load cells within the split axleshafts 232 in the described orientation is the preferred method ofmeasuring forces in the split axle shafts 232, other configurations ofthe load cells for measuring lateral and vertical forces may also beused to achieve the same result.

In the second embodiment, using strain sensors 356, 358, shaft 332includes a spindle 36 at the outboard end 340 of the split axle shaft332. At the inboard ends 352 the hydraulic ram 56 attaches to clevis andpin fittings 359. Spaced in from end 340 is a load/strain region 342.The load/strain region 342 is created by creating opposing recesses 343within the split axle shaft 332. Between the recesses 343 is a centralweb 345. It is preferable that the central web portion 345 beapproximately ½″ in thickness. In the second embodiment, the central webportion 345 of the load/strain region 342 is surface fitted with strainsensors 356, 358, which transmit strain information to the controlsystem. The strain sensors 356, 358 can be attached to the surface ofthe central web portion 345 with adhesive, fasteners or welding. Thecompression or shear deformation of the central web portion 345 ismeasured by the strain sensors, creating an analog signal sent to thesignal conditioning amplifier. The strain information detected by thestrain sensors 356, 358, permits the control system to monitor loadforce on the split axle shafts 332 and vary hydraulic pressure withinthe hydraulic ram 56 to compensate for movement in the track.

Due to the unique advantages of the non-rotating split axle embodimenttaught herein and in U.S. Pat. No. 5,756,903, either load sensors 256,258 or strain sensors 356, 358 can be used to directly measureload/strain on the axle, in a selected direction. Competitive trackstrength testing vehicles with rotating axles cannot be easily adaptedto use of load/strain measurements because of the difficulty ofidentifying the direction of load/strain as the axle rotates. The directforce measurement in the non-rotating axle shaft 332 is continuous alongthe running rail.

The lateral and vertical force control of the gauge restraintmeasurement system is a closed-loop control system that is capable ofmaking continuous changes in force exerted by the hydraulic ram 56 inresponse to force readings provided by the load cells 256, 258. Thisarrangement ensures that a constant force is continuously applied to thetrack as the gauge restraint measurement system is rolling down therailway at speeds varying from 5 mph to 35 mph. It is essential to applya constant lateral and vertical force upon the tracks even while thetracks are moving in response to the force so that an accurate andconsistent measurement of variations in gauge, hence lateral strength ofthe track can be measured to show the extent of lateral weakness of thetrack. As the test vehicle encounters a laterally weak section in thetrack, the track moves in response to the forces, decreasing the load onthe load cells. In response to the decrease in force, the hydraulic ram56 expands increasing the force on the track until the desired force isachieved. Without the increase in force, accurate track gaugemeasurements could not be made.

The closed loop hydraulic control system is designed to maintain aconstant rail/wheel lateral force. This is accomplished by use of ahydraulic servo-valve controlled by force feedback provided by forcetransducers, load cells 256, 258, in the extremity of the split axleshaft 232, closest to the wheel. Using the closed loop system, pressureon the rail does not drop with movement of the track. To maintainconstant pressure on the tracks, the hydraulic servo-valve is used torapidly increase pressure on either side of the hydraulic ram 56. In thepreferred embodiment a Moog 72-102 servo valve is used to supplypressurized fluid to either end of the hydraulic ram 56. The servo-valveincludes a first hydraulic line that connects to a first end of thehydraulic ram 56, and when pressurized, causes the ends of the hydraulicram 56 to move outward exerting additional pressure on the split axleshafts 232. Pressurizing the first hydraulic line, causes the extensionof the hydraulic ram 56 and the extension of the overall length of theaxle assembly 20, which compensates for outward movement of the track.The servo-valve also includes a second hydraulic line that connects to asecond end of the hydraulic ram 56, and when pressurized, causes theends of the hydraulic ram 56 to pull inward, decreasing pressure on thesplit axle shafts 232. Pressurizing the second hydraulic line causes theretraction of the hydraulic ram 56 and an overall decrease in the lengthof the axle assembly 20 to compensate for lack of track movement, i.e.standard track gauge within specifications.

The servo-valve is controlled by the system computer in response tosignals received from the load cells 256, 258. If the load cells 256,258 send a signal showing a drop in force on the track due to tracklateral weakness, the computer sends an analog signal to the servo-valveto increase hydraulic pressure in the first end of the hydraulic ram 56,maintaining constant force on the split axle shafts 232 and expansion ofthe overall length of the axle assembly 20. If the load cells 256, 258send a signal showing an increase in force on the track, due to thetransitioning from a weak section of track to a strong section of track,the computer sends an analog signal to the servo-valve to increasehydraulic pressure in the second end of the hydraulic ram 56,maintaining a constant force on the split axle shafts 232, reducing theoverall length of the axle assembly 20. The closed loop force controlsystem has a fast response time that effectively reacts to changes intrack conditions. The closed loop system pushes the split axle shafts232 outward and pulls the split axle shafts 232 inward to create auniform load on the track. This arrangement creates a highly constantforce on the track, permitting highly accurate track strengthmeasurements.

To measure physical changes in distances between the rails of the trackbeing tested in the preferred embodiment, a laser measurement system isused. While a laser measurement system is utilized, other means formeasuring may also be incorporated such as mechanical means. The frontof the track strength testing vehicle is equipped with an inspectioncamera and laser measurement device to measure unloaded gauge. The lasermeasurement device at the front of the vehicle takes a pre-forcedistance measurement of the track in an unstressed state. Themeasurement data is sent to and recorded by the system computer. Asecond inspection camera and laser measurement device is mounted underthe vehicle adjacent to the load axle 20, and is adapted to measure thedistance between the rails of the track being tested under load. Thevalues collected by the second laser measurement device are recorded bythe system computer. The computer compares the differences between thefirst and second measurements and records the difference. The differencein the track gauge between a loaded and unloaded state in combinationwith the associated forces is used to determine whether a section oftrack is in need of repair.

The direct measurement of load/strain on the split axle shafts 232themselves enables the track strength testing vehicle to acquire andstore load axle force data and provide a graphical display that is usedfor the evaluation of the gauge restraint measurement system GRMS loadaxle performance during revenue service. In addition to the featuresdescribed in U.S. Pat. No. 5,756,903 and the improvements describedabove, this improvement utilizes a computer used for the load cellcalculations, including signal amplification and A/D cards.

Lateral and vertical load values are calculated by the load cellcomputer from input from the load cells 256, 258. The load cell computerused for the load cell calculations uses converter boards to convertamplified and conditioned analog signals developed by the load cellcircuitry to digital values (A/D converter boards). The signalconditioner boosts the analog signal from the load cells 256, 258. TheA/D boards covert the amplified analog signal to a digital signal. TheA/D converter board values can be used for force calculation purposes.The calculated lateral and vertical load values are used as digitalinputs to the program.

The three cameras used in the system have one camera positioned to sendvideo of the track directly ahead of the track strength testing vehicle.This video is used to correlate track conditions with graphical resultsproduced by the program. The video also allows for custom graphproduction during playback mode. The two other cameras used in thesystem send video that allows monitoring load axle wheel performance ina loaded and unloaded state and the lateral and vertical position of theload axle with respect to the vehicle. An illustration of the display400, is shown in FIG. 9.

Camera graphics show the left wheel, 402, right wheel 404 and outsideenvironment 406. Data plots on the left, drivers side, 408 and rightside 410 show the progression of data collection and plot points in a‘scatter plot’ form relative to statistical envelopes 412, 414.Corresponding histograms 416, 418 provide a different statistical viewof the data points. Finally, in the preferred embodiment, an array 420of computer control ‘buttons’ is in the lower center of the display 400.

Typical computer controls will be used to operate the system, includingstart, reset, pause and resume functions, in addition to various datafield entry. The controls are used for such functions as skippingcurves, switches, frogs, constructing custom graphs to show tangentbehavior only or curve behavior only.

A primary function of the system is that of graph-building and retainingaccumulated graphed data, correlated to the odometer and track locationvideo. The graphs plot data points for left and right rails, displayingthe data points as accumulated plots with applied vertical force on the“y” axis and applied horizontal force on the “x” axis. Also displayedare the limits of permissible deviation of the “x” and “y” values froman ‘envelope’ of acceptable force. The general display is shown in FIG.9, while a comparison of data plots in the prior art loaded gauge axletrack strength apparatus compared to the improvement, both using thecomputer monitoring system described above, are shown in FIG. 10 andFIG. 11, respectively.

The system allows the operator to view a two-dimensional graph oflateral and vertical forces displayed on a computer monitor. Atwo-dimensional scatter-graph is displayed for each wheel showing a dotfor each foot of travel along the running rail. Dots are positioned onthe graph with later position relative to the horizontal scale andvertical position relative to the vertical scale calibrated in kips(thousands of pounds). A third dimension is added by color graduation ofthe scatter-graph according to frequency of occurrence. Thus, thegraphical display showing a degree of force control effectiveness ismade available to the operator (and customer). The resulting display isnot unlike a weather-radar image that illustrates different colors forvariations in rain density/intensity. Graphical force distributioninformation is made available to the operator so that he can monitorcontrol system performance. By visually monitoring the forcedistribution scatter-graph, the operator can detect control systemdegradation over time and take corrective action. Pattern recognitionenables an operator to identify a developing problem at the componentlevel, which greatly enhancing the maintainability of the system and theavailability of the system to produce revenue, resulting in significanteconomic benefit for the operator and better service to the customer.

Experimentation has shown the interrelation between the load/strainsensor arrangement and the plots described above. With the prior arthydraulic pressure sensing surrogate for the mechanical properties,points were more frequently outside the permissible ‘envelope’ as shownin FIG. 10. This plot is created using an open loop force controlapparatus, and it is for this reason it is designated as “Prior Art.” Infact, however, the display apparatus is that of the improvement as todisplay and calculations discussed herein. Using the closed loop controlsystem, greater precision and fewer false indications of inadequatestrength are received. This is shown in FIG. 11. It will be observedthat the data points plotted 422 using the open loop system covers amuch larger area of the graph than plot 424, using the closed loopsystem.

The track strength measurement system can be quickly calibrated withoutthe need to send the system to an independent laboratory that could takea measurement vehicle offline for several weeks, causing loss inrevenue. Accordingly, an additional feature of the track strengthmeasurement system is the Load Axle Calibration Subsystem, hereaftersometimes abbreviated “LACS”.

The purpose of the LACS application is to automatically incrementvertical and lateral hydraulic pressures in a planned sequence whilesimultaneously acquiring load axle load cell force data and comparing topermanently installed NIST traceable transfer standard load cells 460,462, hereinafter referred to as transfer standard cells, in order togenerate correction constants for the load cell correction applicationas a field calibration procedure, as shown in FIGS. 3 and 4. Thisself-contained system directly compares the transfer standard cells 460,462 with the force measurement signals generated by the internalload-axle load cells and establishes a linear mathematical relationshipthat is stored in the measurement system computer. The system utilizesthe transfer standard cells 460, 462 that independently measure theforce applied to the wheels 46 by the hydraulic cylinders 82. Thetransfer standard cells 460, 462 can be removed from the vehicle andsent to a testing center to ensure their accuracy. A spare set oftransfer standard cells 460, 462 can be retained so that the vehicle isnot out of service. Typically the transfer standard cells 460, 462 needto be calibrated once a year to ensure accuracy.

The entire calibration procedure of the load axle 20 takes approximately10–15 minutes. The application automatically installs calibrationconstants for the load cell correction application and prints acalibration report for distribution to the customer.

The LACS system utilizes vertical polyester web straps 450, 452 tosupport wheels 46 and a lateral polyester web strap 454 to restrictlateral movement of the wheels 46 as shown in FIGS. 3 and 4. Whilepolyester web straps are preferred, other types of material andharnesses may be used to restrict vertical and lateral movement. Acentering device is incorporated on top of the load axle 20 duringcalibration to center the axle ensuring vertical loading. Vertical loadsare sensed by transfer standard cells 460, 462 and lateral loads aresensed by transfer standard cell 464. The vertical load cells 256 aretested by use of transfer standard cells 460, 462. The calibrationprocedure can be performed in a hotel parking lot prior to starting thetrack testing work day.

To calibrate the system, the operator places the vertical polyester webstraps 450, 452 over the wheels 46 and connects the ends of thepolyester web straps 450, 452 to a transfer standard cell supportbracket 463. A separate support bracket 456 is directly connected to afirst end of each of the transfer standard cells 460, 462. The transferstandard cells 460, 462 are connected to the vehicle at a second end.Once the polyester web straps 450, 452 are in position around the wheels46, the hydraulic cylinders 82 are expanded incrementally to testvertical load cells 256. The hydraulic cylinders 82 are moved downwardwith ten increments of increasing force. The test begins with a load of2,000 lbs vertical force applied to the split axle shafts 232 and movesupward in ten equal increments until 15,000 lbs of vertical force isachieved. The vertical force values detected by the transfer standardcells 460, 462 are compared to the vertical force values detected by theload cells 256. If the vertical force measured from the load cells 256varies from the vertical force measured by the transfer standard cells460, 462, the load cells 256 are recalibrated to match the values of thetransfer standard cells 460, 462.

To calibrate lateral load force, a polyester web strap 454 is attachedto the wheels 46 by use of brackets to restrict lateral movement of thewheels. The transfer standard cell 464 is fitted to the lateralpolyester web strap 454 so that an independent lateral load can bedetected. Once the lateral polyester web strap 454 and transfer standardcell 464 are in position, the hydraulic ram 56 is expanded in 10 equalincrements from 2,000 lbs to 9,000 lbs so that test values can begathered. The lateral force values measured by the transfer standardcell 464 are compared to the lateral force values measured by the loadcells 258. The analog signal from the load cells 258 are assigned anumerical force value, which is compared to the output reading of thetransfer standard cell 454. If the lateral force value gathered from theload cells 258 varies from the lateral force output reading of thetransfer standard cell 454, the values assigned to the output of theload cells 258 are recalibrated to match the load values of the lateralstrains sensor 454. The NIST transfer standard cells 460, 462, 464 arecalibrated annually to maintain traceability for GRMS system calibrationand performance.

Calibration files are retained and used to maintain a historicalstatistical quality assurance graph for the detection of gradual orabrupt system changes. The statistical quality assurance graph is usedas a maintenance and monitoring tool by both field crew and engineeringstaff as a maintenance and design decision making tool.

In the preferred embodiment, the calibration subsystem uses a cPCI QNXprocessor and cPCI analog/digital A/D converter in 3U Eurocard chassis.This will be operatively connected to a server used for the host programincluding A/D cards and D/A cards. Measurements are provided by transferstandard cells from Sensotec model AL416EL or similar from OmegaEngineering.

The LACS hardware 500 to support the transfer standard cells 460, 462,464 will be mounted beneath the truck body above the load axle wheels asshown in FIGS. 3 and 4. Signal conditioning will be used for the threetertiary standard load transducers to amplify the analog signals fromthe load transducers.

Lateral 502, and vertical force values 504, 506, from transfer standardcells 460, 462, 464 are fed from the three signal conditioner amplifiers508, 510 and 512 into three available channels of the LC computer A/Dcard as shown in FIG. 12. The cPCI computer 514 used for the load cellcalculations uses an A/D converter to convert analog signals developedby the axle load cell circuitry to digital values that can be used forforce calculation purposes. These raw lateral and vertical force valuesare fed through the signal conditioner 516 and then directly through theload cell computer 514 as uncorrected values and used as digital inputsto the calibration program running on the host computer.

As the calibration operation is performed, progress of the testprocedure, verification of performance within specifications or failure,and documentation of identification, time, specification and reportingof same will be displayed and provided.

Various features of the disclosure have been shown and described inconnection with the illustrated embodiment, however, it is understoodthat these arrangements merely illustrate, and that the disclosure is tobe given its fullest interpretation.

1. A railway track strength measurement system comprising: an axleassembly having a first wheel and a second wheel, the wheels positionedto ride on railway track; a first axle half connected to the first wheeland a second axle half connected to the second wheel; the first andsecond axle halves being interconnected by an expansion device, theexpansion device adapted to increase and decrease the distance betweenthe first and second wheels and places a lateral load on the axle halvesand track; and the axle halves each including force sensors adapted tomeasure changes in lateral forces in the axle halves; the compressiondevice includes a hydraulic ram connected to the first axle half at afirst end and to the second axle half at a second end; the first andsecond axle halves are fixed and do not rotate with respect to the firstand second wheels; said first axle half includes a load measurementregion; the load measurement region is formed to define two opposedvertical recesses, with a solid portion positioned between the tworecesses; wherein the solid portion includes two apertures adapted toreceive load cells.
 2. The railway track strength measurement system ofclaim 1, wherein one of the load cells are positioned within theapertures to detect lateral forces with the axle halves.
 3. A railwaytrack strength measurement system comprising: an axle assembly having afirst wheel and a second wheel the wheels positioned to ride on railwaytrack; a first axle half connected to the first wheel and a second axlehalf connected to the second wheel; the first and second axle halvesbeing interconnected by an expansion device, the expansion deviceadapted to increase and decrease the distance between the first andsecond wheels and places a lateral load on the axle halves and track;and the axle halves each including force sensors adapted to measurechanges in lateral forces in the axle halves; the first and second axlehalves are connected to a pair of hydraulic cylinders, the hydrauliccylinders positioned to place a vertical load on the axle halves; theaxle halves each include force sensors adapted to measure changes invertical forces in the axle halves.
 4. A method for measuring trackstrength comprising the steps of: positioning a track strength measuringdevice on a pair of railway rails, the rail strength measuring devicehaving a pair of adjustable axle halves positioned between a pair ofwheels; placing the pair of axles under a substantially constant lateralload; measuring force in a given region in each of the axle halves;recording force from the given region in each of the axle halves;measuring changes in track gauge from an unloaded to a loaded state; anddetermining, based on changes in track gauge from an unloaded to aloaded state in combination with known loading forces, whether portionsof the track are in need of repair.
 5. The method for measuring trackstrength of claim 4, further including the step of comparing themeasured track gauge under load to known standard values.
 6. The methodfor measuring track strength of claim 5, further including the step ofrepairing the section of track that does not meet the known standardvalues.
 7. A railway track strength measurement system comprising: anaxle assembly having a first wheel and a second wheel, the wheelsadapted to ride on railway rails; a first axle half connected to thefirst wheel and a second axle half connected to the second wheel; thefirst and second axle halves being interconnected by a first hydrauliccylinder, the hydraulic cylinder adapted to place a lateral force on theaxle halves; the first axle half have being connected to a secondhydraulic cylinder the second hydraulic cylinder adapted to place avertical force on the first axle half; the second axle half beingconnected to a third hydraulic cylinder, the third hydraulic cylinderadapted to place a vertical force on the second axle half; the first andsecond axle halves each including load sensors adapted to measurechanges in vertical and lateral forces within the first and second axlehalves.
 8. The railway track strength measurement system of claim 7wherein the first and second axle halves are fixed and do not rotatewith respect to the first and second wheels.
 9. An axle continuouslateral and vertical force control system comprising: first and a secondaxle halves each having a wheel, the wheels adapted to ride upon railwaytracks; each of the axles including force sensors adapted to measurelateral and vertical load on the axles; a first hydraulic cylinderadapted to exert a lateral force on the axles, causing a lateral forceto be applied to the railway tracks; a second hydraulic cylinder adaptedto exert a vertical force on the axles, causing a vertical force to beapplied to the railway tracks; a controller adapted to receive signalsfrom the force sensors and adapted to react to variations in signals bymaking computations as to the force needed to counteract the variationsin signals; a hydraulic servo valve system adapted to receive signalsfrom the controller and independently pressurize the hydraulic cylindersat a first end to independently decrease lateral or vertical load on theaxles or to pressurize the hydraulic cylinders at a second end toindependently increase lateral or vertical load on the axles, inresponse to variations in signals from the force sensors.